: The investigators aim to permanently thrombose aneurysmal sacs by an endovascular approach. They will do this in experimental aneurysms. They have recently developed microcatheters and microguide wires which have the physical characteristics to enable them to enter aneurysms traumatically without requirement for general anesthesia or craniotomy. The tip of a 2.2 F microcatheter is positioned in the neck of an experimentally created carotid artery aneurysm and via this catheter a soft platinum tip of a stainless steel microguide wire (0.010 in. diameter) is placed in the aneurysm. A positive 0.5 mA direct electric current applied via the guidewire stimulates the formation of intraaneurysmal thrombus. Blood elements are negatively charged and are attracted to the positively charged platinum tip. Following complete aneurysmal occlusion, a 0.5 mA positive direct current is again applied to the microguide wire to detach its platinum tip within the clotted aneurysm by electrolysis. Knowledge gained from this study should serve as a scientific basis for the clinical treatment of saccular intracranial aneurysms via the endovascular approach which would obviate surgical intervention and its associated mortality/morbidity.